In related art, a configuration of a vehicle seat where a seat back is coupled to a seat cushion via a recliner so that a backrest angle can be adjusted has been known (JP-A-2013-22409). The recliner has a ratchet and a guide mounted to be rotatable relative to each other and a lock mechanism capable of locking the relative rotation between the ratchet and the guide. The lock mechanism has a configuration where a plurality of poles set to the guide is meshed with inner circumferential teeth formed on an outer circumferential part of the ratchet and the relative rotation between the ratchet and the guide is thus locked.
Specifically, the plurality of poles is supported in a circumferential direction by the guide and is pushed outwards in a radial direction to be moved, so that outer circumferential teeth thereof are meshed with the inner circumferential teeth of the ratchet. Also, one of the plurality of poles is configured as a division pole bisected obliquely in the circumferential direction and is pushed outwards in the radial direction to be moved, so that the pole is pushed in a form of increasing a width in the circumferential direction and is meshed with the inner circumferential teeth of the ratchet without the backlash relative to the guide in the circumferential direction. In this way, the ratchet and the guide are kept via the division pole without the backlash in the circumferential direction and the rotation is stopped.
In the above technology of the related art, the pole is divided, so that the number of components increases. In addition, since it is necessary to mount the divided small pieces to a narrow space, the manufacturing cost increases.